#include "stm32f10x.h"
void delay_nms(u16 time);
void TIM3_PWM_Init(u16 arr, u16 psc);

int main() {
    u16 led0pwmval = 0;
    u8 dir = 1;

    TIM3_PWM_Init(899, 0);  //不分频。PWM频率=72000/(899+1)=80Khz
    while (1) {
        delay_nms(10);
        if (dir)
            led0pwmval++;
        else
            led0pwmval--;
        if (led0pwmval > 200) dir = 0;
        if (led0pwmval == 0) dir = 1;
        TIM_SetCompare2(TIM3, led0pwmval);
    }
}

// PWM输出初始化
// arr：自动重装值
// psc：时钟预分频数
void TIM3_PWM_Init(u16 arr, u16 psc) {
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);  //
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO,
                           ENABLE);  //使能GPIO外设时钟使能

    GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE);  // 重映射到PA7 --> PB5

    //设置该引脚为复用输出功能,输出TIM3 CH2的PWM脉冲波形
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;        // TIM_CH2
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  //复用推挽输出
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    TIM_TimeBaseStructure.TIM_Period =
        arr;  //设置在下一个更新事件装入活动的自动重装载寄存器周期的值	 80K
    TIM_TimeBaseStructure.TIM_Prescaler =
        psc;  //设置用来作为TIMx时钟频率除数的预分频值  不分频
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;  //设置时钟分割:TDTS = Tck_tim
    TIM_TimeBaseStructure.TIM_CounterMode =
        TIM_CounterMode_Up;  // TIM向上计数模式
    TIM_TimeBaseInit(
        TIM3,
        &TIM_TimeBaseStructure);  //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位

    TIM_OCInitStructure.TIM_OCMode =
        TIM_OCMode_PWM2;  //选择定时器模式:TIM脉冲宽度调制模式2
    TIM_OCInitStructure.TIM_OutputState =
        TIM_OutputState_Enable;  //比较输出使能
    TIM_OCInitStructure.TIM_Pulse = 0;  //设置待装入捕获比较寄存器的脉冲值
    TIM_OCInitStructure.TIM_OCPolarity =
        TIM_OCPolarity_High;  //输出极性:TIM输出比较极性高
    TIM_OC2Init(
        TIM3,
        &TIM_OCInitStructure);  //根据TIM_OCInitStruct中指定的参数初始化外设TIMx

    TIM_CtrlPWMOutputs(TIM3, ENABLE);  // MOE 主输出使能

    TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);  // CH2预装载使能

    TIM_ARRPreloadConfig(TIM3, ENABLE);  //使能TIMx在ARR上的预装载寄存器

    TIM_Cmd(TIM3, ENABLE);  //使能TIM1
}

void delay_nms(u16 time)  //延时子程序
{
    u16 i = 0;
    while (time--) {
        i = 12000;  //自己定义
        while (i--)
            ;
    }
}
